1. Field of the Invention
The present invention relates to a semiconductor device package used in an optical transmitter-receiver circuit, mounting photo semiconductor devices or semiconductor devices on a circuit substrate.
2. Related Art of the Invention
When the application of optical fiber communications to CATV systems or mobile communications is considered, the optical transmitter-receiver is required to have properties to transmit analog signals with a broad area at a high speed. A system including photo semiconductor devices to be connected to optical fibers, and semiconductor devices for inputting/outputting of high frequency electrical signals in and from the photo semiconduct or devices, is used for optical communications.
FIG. 5 shows a conventional photo semiconductor and semiconductor device package. Here, an optical receiver will be described. Light from an optical fiber 100 enters into a photo diode (PD) 200, which is a photo semiconductor device having a light receiving function, from the obliquely ground and polished end. Signals photo-electrically converted by the PD 200 are inputted in a semiconductor device 300, which has a pre-amplifying function to amplify signals with low noise, and are amplified. The signals are then guided to a next-stage semiconductor device 400 for processing.
The photo semiconductor device (PD) 200, the semiconductor devices 300 and 400, and peripheral parts 122 and 132 are mounted on the same surface of a high-frequency circuit substrate 80, which is disposed and fixed on a housing base 70. Here, the photo semiconductor device 100 and the semiconductor devices 200 and 300 are mounted by flip chip bonding (FCB) using under fills 1000.
In the above-described structure, the distances between photo semiconductor devices and semiconductor devices adjacent to each other must be, for example, 0.3 mm or more in order to prevent under fills from overlapping, or to secure spaces for mounting peripheral parts even if no under fills are used. On the other hand, however, it is preferable that the distance between the photo semiconductor device and the next stage semiconductor device is as small as possible.
Also, since semiconductor devices having amplifying functions generate heat, the semiconductor devices are provided with heat-radiating mechanisms for radiating heat efficiently. However, the above-described structure may become complicated because the heat-radiating mechanism is disposed on the upper surface of the semiconductor devices shown in the diagram.
Although not shown in the diagram, a method of the heat radiation of semiconductor devices is performed by forming a hole to accommodate the semiconductor devices on the high-frequency circuit substrate 80, disposing the semiconductor devices on the housing base 70 upside down, and electrically connecting to the high-frequency circuit substrate 80 using wire bonding. However, since this is different from the semiconductor device packaging method, new production facilities for packaging different from the method of packaging photo semiconductor devices must be introduced in the actual manufacturing process, resulting in raising the costs of semiconductor device packages.
The object of the present invention is to solve the above-described problems, and to provide a semiconductor device package that can mount photo semiconductor devices and semiconductor devices close to each other as much as possible, radiates the heat of the semiconductor devices effectively, and can reduce- the size; and an optical communication device using such a semiconductor device package.
The 1st invention of the present invention is a semiconductor device package, comprising:
a heat radiating base that has a depression;
a circuit substrate disposed on said heat radiating base so as to cover at least said depression; and
at least two semiconductor devices at least one of which is mounted on each of one and the other major surfaces of said circuit substrate,
wherein said semiconductor device mounted on one major surface of said circuit substrate coupled to said heat radiating base is disposed in said depression, and is coupled to at least a part of said depression with good thermal conductivity.
The 2nd invention of the present invention is the semiconductor device package according to 1st invention,
wherein said semiconductor device comprises at least one photo semiconductor device, and
said semiconductor device package further comprises an optical fiber or an optical wave-guide for inputting and outputting lights to and from said photo semiconductor device.
The 3rd invention of the present invention is the semiconductor device package according to 2nd invention,
wherein said semiconductor devices are mounted on the other major surface of said circuit substrate that is not coupled to said heat radiating base, and is connected to said semiconductor devices disposed in said depression.
The 4th invention of the present invention is the semiconductor device package according to 2nd invention,
wherein said semiconductor devices are mounted on the other major surface of said circuit substrate that is not coupled to said heat radiating base, and
all of said semiconductor devices other than said photo semiconductor device are mounted in said depression.
The 5th invention of the present invention is the semiconductor device package according to 1st or 2nd inventions, wherein said semiconductor devices mounted on one major surface of said circuit substrate that is coupled to said heat radiating base is fixed to the surface of said depression with a heat-conductive resin.
The 6th invention of the present invention is the semiconductor device package according to 1st or 2nd inventions, wherein said semiconductor devices are electrically connected to said circuit substrate with an electrically conductive resin.
The 7th invention of the present invention is the semiconductor device package according to 1st or 2nd inventions, wherein the dielectric constant of a part of said circuit substrate is different from the dielectric constant of other parts.
The 8th invention of the present invention is the semiconductor device package according to 7th invention, wherein the dielectric constant of said part of said circuit substrate is larger than the dielectric constant of said circuit substrate.
The 9th invention of the present invention is the semiconductor device package according to 7th invention, wherein said circuit substrate has a lamination structure, and
said lamination structure comprises layers of materials having dielectric constants different from that of adjacent layers.
The 10th invention of the present invention is the semiconductor device package according to 9th invention, wherein said circuit substrate has an independent electrode disposed on said other major surface,
a part of the electrodes of said semiconductor device is mounted on said independent electrode, and said independent electrode and said material of a different dielectric constant form a capacitor inside said circuit substrate.
The 11th invention of the present invention is the semiconductor device package according to 10th invention, wherein said electrodes of said semiconductor device are power supply terminals or bias terminals to said semiconductor device.
The 12th invention of the present invention is the semiconductor device package according to 1st or 2nd inventions, wherein said circuit substrate has via holes across the both major surfaces thereof, and
at least two semiconductor device""s mounted on one and the other major surfaces of said circuit substrate are electrically connected through said via holes at the distance of the thickness of said circuit substrate.
The 13th invention of the present invention is the semiconductor device package according to 2nd invention, wherein said optical wave-guide or said optical fiber is disposed in said circuit substrate.
The 14th invention of the present invention is the semiconductor device package according to 2nd invention, wherein said heat radiating base is provided with a first guide groove or a marker for locating said optical fiber.
The 15th invention of the present invention is the semiconductor device package according to 2nd invention, wherein said circuit substrate is provided with a second guide groove for disposing said optical wave-guide or said optical fiber.
The 16th invention of the present invention is the semiconductor device package according to 1st or 2nd inventions, wherein said semiconductor devices mounted on said circuit substrate, or said semiconductor devices and said optical wave-guide or said optical fiber are molded in an insulating resin.
The 17th invention of the present invention is the semiconductor device package according to 1st invention, wherein said circuit substrate is connected and fixed to said heat radiating base with an electrically conductive resin.
The 18th invention of the present invention is the semiconductor device package according to 2nd or 13th inventions, wherein said optical wave-guide or said optical fiber has a reflecting structure to receive and reflect light obliquely against the wave-guide direction of said light, and is optically connected to said photo semiconductor device.
The 19th invention of the present invention is an optical communication device that can be used as an optical transmitter or an optical receiver, comprising:
the semiconductor device package according to any one of 1st to 18th inventions;
modulating means or demodulating means; and
transmitting means or receiving means.
According to the present invention, as described above, since photo semiconductor devices are electrically connected to semiconductor devices in close vicinity to each other, heat generated from semiconductor devices can be radiated effectively with out degrading high frequency characteristics. However, the term xe2x80x9csemiconductor devicexe2x80x9d used herein generally represents a light emitting,element or light receiving element consisting of a semiconductor such as a semiconductor laser, an LED, and a photo diode, and also includes a composite element containing light emitting and light receiving elements. Although a photo semiconductor device has the same shape as a semiconductor device, the site for inputting/outputting light is located at the electrode side of the semiconductor device, or the back or side thereof.